730 The Trials of Oil Engines at Cambridge. 
power per hour would be for Messrs. Hornsby’s engine 0'42d. 
and for Messrs. Crossley’s O' 4 Id. There is therefore little dif- 
ference between them on a continuous run. 
Indicator diagrams for the six engines are given in figs. 17 
to 22 (pp. 724, 725, 727). They are copies of the indicator 
cards which approach nearest to the mean during the full-power 
run, and have all been plotted to the same vertical scale. They 
all closely resemble the diagram from an “ Otto ” gas engine, 
and the most marked difference between them is in the initial 
and mean pressures. Messrs. Crossley’s diagram (fig. 18) has 
an initial pressure of 240 lb. per square inch and a mean of 
72 lb., while Messrs. Hornsby’s (fig. 17) has an initial pressure 
of 125 lb., and a mean of 29 lb. On the Britannia Co.’s card 
(fig. 22) only three diagrams have been shown, for the sake of 
clearness. A half-minute card has the whole space between 
maximum aud minimum filled with a succession of diagrams 
varying in sharpness of ignition. 
On the half-power trials the engine which showed itself the 
most economical was the “Campbell,” using T3 lb. of oil per 
brake horse-power hour, to Messrs. Crossley’s T33 lb. and 
Messrs. Hornsby’s T49 lb. In steadiness, however, the 
“Campbell” left much to be desired, and on the light trial 
raced badly. 
Messrs. Weyman’s engine was run twice on the half-load 
trial, the lamp and engine oil having been accidentally mixed 
on the first run. The results were very closely concordant, and 
those given are for the second run. For steadiness at half- 
power and running light this engine is to be commended, its 
action being very regular and uniform. 
The engines of Messrs. Hornsby, Messrs. Crossley, and 
Messrs. Wells, behaved also admirably in this respect. 
The Britannia Co.’s engine showed a considerable tendency 
to race, though to a less extent than the “ Campbell.” On the 
light trial it used less oil per hour than any other engine, but 
in comparing the relative economies due account must be taken 
of the sizes of the different engines. 
Not one of these engines can be pronounced a bad engine. 
With one exception they all proved more economical on their 
full-power efficiency trial than the oil engines tried at Plymouth 
in 1890. But the two which in all-round excellence for farm 
purposes showed themselves throughout these trials superior to 
all the others were undoubtedly those of Messrs. Hornsby and 
Messrs. Crossley. 
For simplicity, reliability, steadiness, minimum of attendance, 
and ease of starting, Messrs. Hornsby’s engine leaves little to 
